The diameter of a 120 cm long roller is 84 cm. It takes 500 complete revolutions of the roller to level a ground. The cost of levelling the ground at Rs. 1.50 sq. m. is:

Solution (By Examveda Team)

According to the question,
Diameter = 84 cm
Radius = 42 cm = 0.42 m
Height = 120 cm = 1.2 m
CSA of cylinder = 2πrh
$$ = 2 \times \frac{{22}}{7} \times 0.42 \times 1.2$$
Total area covered to planed in 500 rounds
$$\eqalign{ & = 2 \times \frac{{22}}{7} \times 0.42 \times 1.2 \times 500 \cr & {\text{Total cost}} = \left( {2 \times \frac{{22}}{7} \times 0.42 \times 1.2 \times 500} \right) \times 1.50 \cr & = {\text{Rs}}{\text{. }}2376 \cr} $$